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Pulmonary arterial remodeling is a pathological process seen in a number of clinical disease states, driven by inflammatory cells and mediators in the remodeled artery microenvironment. In murine models, Th2 cell-mediated immune responses to inhaled antigens, such as purified Aspergillus allergen, have been reported to induce remodeling of pulmonary arteries. We have previously shown that repeated intranasal exposure of healthy C57BL/6 mice to viable, resting Aspergillus fumigatus conidia leads to the development of chronic pulmonary inflammation and the coevolution of Th1, Th2, and Th17 responses in the lungs. Our objective was to determine whether repeated intranasal exposure to Aspergillus conidia would induce pulmonary arterial remodeling in this mixed Th inflammatory microenvironment. Using weekly intranasal conidial challenges, mice developed robust pulmonary arterial remodeling after eight exposures (but not after two or four). The process was partially mediated by CD4 + T cells and by interleukin-4 (IL-4) production, did not require eosinophils, and was independent of gamma interferon (IFN-γ) and IL-17. Furthermore, remodeling could occur even in the presence of strong Th1 and Th17 responses. Rather than serving an anti-inflammatory function, IL-10 was required for the development of the Th2 response to A. fumigatus conidia. However, in contrast to previous studies of pulmonary arterial remodeling driven by the A. fumigatus allergen, viable conidia also stimulated pulmonary arterial remodeling in the absence of CD4 + T cells. Remodeling was completely abrogated in IL-10 −/− mice, suggesting that a second, CD4 + T cell-independent, IL-10-dependent pathway was also driving pulmonary arterial remodeling in response to repeated conidial exposure.

Aspergillus fumigatus-sensitized CCR4-deficient (CCR4−/−) mice exhibit an accelerated clearance of conidia during fungal asthma. In the present study, we examined the roles of CCL17 and CCL22, two CCR4 ligands, during pulmonary invasive aspergillosis in neutropenic mice. Kaplan-Meier survival curve analysis revealed that wild-type C57BL/6 (CCR4+/+) mice were significantly protected from the lethal effects ofAspergilluscompared with their wild-type controls following systemic neutralization with anti-CCL17 but not anti-CCL22 antibodies. Systemic neutralization of CCL17 significantly increased whole-lung CCL2 levels. Mouse survival and histological analysis revealed that the receptor mediating the deleterious effects of CCL17 was CCR4 since mice genetically deficit in CCR4 (CCR4−/−) did not develop invasive aspergillosis. Enzyme-linked immunosorbent assay analysis of whole-lung samples at day 2 after conidial challenge in neutrophil-depleted CCR4−/−and CCR4+/+mice revealed that whole-lung IL-12 levels were significantly increased in the CCR4−/−group compared with the wild-type group. Also at day 2 after conidial challenge, significantly greater numbers of CD11c+F4/80+and CD11c+/CD86+but fewer CD3/NK1.1+cells were present in the lungs of CCR4−/−mice compared with their wild-type counterparts. Thus, CCL17-CCR4 interactions dramatically impair the pulmonary antifungal response againstA. fumigatusin neutropenic mice.

The rat tapewormHymenolepis diminutawas used to test the hypothesis that helminth infection could modulate murine colitis. Mice were infected with fiveH. diminutacysticercoids, and colitis was evoked via free access to 4% (wt/vol) dextran sulfate sodium (DSS)-containing drinking water for 5 days. BALB/c mice were either infected withH. diminutaand 7 days later exposed to DSS (prophylactic strategy) or started on DSS and infected withH. diminuta48 h later (treatment strategy). Naive andH. diminuta-only-infected mice served as controls. On autopsy, colonic segments were processed for histological examination and myeloperoxidase (MPO) measurement or mounted in Ussing chambers for assessment of epithelial ion transport. Cytokines (gamma interferon [IFN-γ], interleukin 12 [IL-12], and IL-10) were measured in serum and colonic tissue homogenates. DSS treatment resulted in reduced ion responses (indicated by short-circuit current [Isc]) to electrical nerve stimulation, the cholinergic agonist carbachol, and the adenylate cyclase activator forskolin compared to controls.H. diminutainfection, either prophylactic or therapeutic, caused a significant (P< 0.05) amelioration of these DSS-induced irregularities in stimulated ion transport. In contrast, the histopathology (i.e., mixed immune cell infiltrate, edema, and ulcerative damage) and elevated MPO levels that accompany DSS colitis were unaffected by concomitantH. diminutainfection. Similarly, there were no significant differences in levels of IFN-γ, IL-12, or IL-10 in serum or tissue from any of the treatment groups at the time of autopsy. We suggest that abolishment of colitis-induced epithelial ion transport abnormalities byH. diminutainfection provides proof-of-principle data and speculate that helminth therapy may provide relief of disease symptoms in colitis.

Previous studies have suggested that the C-C chemokine C10 is involved in the chronic stages of host defense reactions. The present study addressed the role of C10 in a murine model of septic peritonitis, induced by cecal ligation and puncture (CLP). Unlike other C-C chemokines, C10 levels in the peritoneal wash were increased approximately 30-fold above baseline levels at 48 h after CLP surgery. Immunoneutralization of peritoneal C10 levels with polyclonal anti-C10 antiserum during CLP-induced peritonitis negatively impacted mouse survival over 4 days. In contrast, when 500 ng of recombinant murine C10 was administered immediately after CLP surgery, the 4-day survival rate increased from 20% to over 60%. The C10 therapy appeared to facilitate a rapid and significant enhancement of the levels of tumor necrosis factor alpha (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) and a later increase in interleukin-13 (IL-13) levels in the peritoneal cavity. In vitro studies showed that the combination of IL-1β and C10 markedly augmented TNF-α synthesis by peritoneal macrophages and that C10 synthesis was induced in these cells following their exposure to IL-13. At 24 h after CLP surgery, only 25% of C10-treated mice were bacteremic versus 85% of the control group that exhibited dissemination of bacteria into the circulation. The lack of bacteremia in C10-treated mice appeared to be related, in part, to in vitro evidence that C10 significantly enhanced the bacterial phagocytic activity of peritoneal macrophages. In addition, in vivo evidence suggested that C10 therapy significantly reduced the amount of material that leaked from the damaged gut. Taken together, the results of this study demonstrate that the C10 chemokine rapidly promotes disease resolution in the CLP model through its direct effects on the cellular events critically involved in host defense during septic peritonitis.

Bacterial superantigens (SAgs) have been implicated in inflammatory disease, and SAg-treated mice have increased jejunal T cells. Here we show that T84 cells (a human epithelial cell line) display increased MCP-1 and RANTES mRNA expression and protein production in response to conditioned medium from Staphylococcus aureus enterotoxin B (SEB; a model SAg)-activated immune cells. Also, MCP-1 and RANTES mRNAs were increased in jejunal enterocytes isolated from SEB-treated mice. We suggest that T-cell recruitment to the gut following SAg immune activation could be partially due to epithelium-derived chemokines.

This study demonstrates that the therapeutic effect of a nitric oxide inhibitor in a murine model of fecal peritonitis is mediated in part by increased levels of interleukin-10 (IL-10) and monocyte chemoattractant protein 1 (MCP-1). Female CD1 mice were subjected to cecal ligation and puncture (CLP) with a 21-gauge needle and, immediately following surgery, were injected intraperitoneally with saline, N G -nitro- l -arginine methyl ester ( l -NAME; 8 mg/kg), or N G -nitro- d -arginine methyl ester ( d -NAME; 8 mg/kg). At 96 h after surgery and drug treatment, 20% of mice that received d -NAME had survived whereas 60% of mice that received l -NAME were alive. To elucidate the effect of l -NAME treatment on chemokine and cytokine production during fecal peritonitis, the levels of macrophage inflammatory protein 2 (MIP-2), IL-10, and MCP-1 were measured in peritoneal washings from additional groups of mice 24 h after the CLP surgery. Peritoneal fluids from l -NAME-treated mice contained significantly higher levels of IL-10 and MCP-1 than did those from d -NAME-treated mice. To elucidate the effect of nitric oxide inhibition on potential cellular sources of IL-10 and MCP-1 in the CLP model, cultured alveolar and peritoneal macrophages were activated with bacterial lipopolysaccharide in the presence of l -NAME; these macrophages produced significantly more MCP-1 than did similarly activated macrophages in the presence of d -NAME. In the CLP surgery model, immunoneutralization of IL-10 alone or IL-10 and MCP-1 together with polyclonal antibodies prior to surgery significantly reduced the survival rates in l -NAME-treated groups compared with l -NAME-treated groups that received preimmune serum. Taken together, these data demonstrate that the inhibition of nitric oxide following experimental CLP fecal peritonitis is therapeutic, in part through the modulatory effect of this treatment on the synthesis of IL-10 and MCP-1.

Pulmonary arterial remodeling is a pathological process seen in a number of clinical disease states, driven by inflammatory cells and mediators in the remodeled artery microenvironment. In murine models, Th2 cell-mediated immune responses to inhaled antigens, such as purified Aspergillus allergen, have been reported to induce remodeling of pulmonary arteries. We have previously shown that repeated intranasal exposure of healthy C57BL/6 mice to viable, resting Aspergillus fumigatus conidia leads to the development of chronic pulmonary inflammation and the coevolution of Th1, Th2, and Th17 responses in the lungs. Our objective was to determine whether repeated intranasal exposure to Aspergillus conidia would induce pulmonary arterial remodeling in this mixed Th inflammatory microenvironment. Using weekly intranasal conidial challenges, mice developed robust pulmonary arterial remodeling after eight exposures (but not after two or four). The process was partially mediated by CD4+ T cells and by interleukin-4 (IL-4) production, did not require eosinophils, and was independent of gamma interferon (IFN-γ) and IL-17. Furthermore, remodeling could occur even in the presence of strong Th1 and Th17 responses. Rather than serving an anti-inflammatory function, IL-10 was required for the development of the Th2 response to A. fumigatus conidia. However, in contrast to previous studies of pulmonary arterial remodeling driven by the A. fumigatus allergen, viable conidia also stimulated pulmonary arterial remodeling in the absence of CD4+ T cells. Remodeling was completely abrogated in IL-10−/− mice, suggesting that a second, CD4+ T cell-independent, IL-10-dependent pathway was also driving pulmonary arterial remodeling in response to repeated conidial exposure.

The role of Toll-like receptor 9 (TLR9) in antifungal responses in the immunodeficient and allergic host is unclear. We investigated the role of TLR9 in murine models of invasive aspergillosis and fungal asthma. Neutrophil-depleted TLR9 wild-type (TLR9+/+) and TLR9-deficient (TLR9−/−) mice were challenged with resting or swollenAspergillus fumigatusconidia and monitored for survival and lung inflammatory responses. The absence of TLR9 delayed, but did not prevent, mortality in immunodeficient mice challenged with resting or swollen conidia compared to TLR9+/+mice. In a fungal asthma model, TLR9+/+and TLR9−/−mice were sensitized to solubleA. fumigatusantigens and challenged with resting or swollenA. fumigatusconidia, and both groups of mice were analyzed prior to and at days 7, 14, and 28 after the conidium challenge. When challenged with resting conidia, TLR9−/−mice exhibited significantly lower airway hyper-responsiveness compared to the TLR9+/+groups. In contrast,A. fumigatus-sensitized TLR9−/−mice exhibited pulmonary fungal growth at days 14 and 28 after challenge with swollen conidia, a finding never observed in their allergic wild-type counterparts. Increased fungal growth in allergic TLR9−/−mice correlated with markedly decreased dectin-1 expression in whole lung samples and isolated dendritic cell populations. Further, whole lung levels of interleukin-17 were lower in allergic TLR9−/−mice compared to similar TLR9+/+mice. Together, these data suggest that TLR9 modulates pulmonary antifungal immune responses to swollen conidia, possibly through the regulation of dectin-1 expression.